The present invention relates to joint sealing members used for effecting water stopping processing at junctions of members used for civil engineering works or the like.
For example, as shown in Fig s. 1, 2A and 3, plural unit segments 1 are used as work materials in constructing a shield tunnel excavated underground. These unit segments 1 are closely joined in the direction a along the peripheral wall and in the longitudinal direction b of the gallery.
At the four sides of a plate portion of each of the segments 1, there are provided front and rear flanges 2 and 3 extending in the circumferential direction a around the peripheral walls, and upper and lower flanges 4 and 5 extending in the longitudinal direction b. When these segments are joined, the adjacent flanges 2 and 3, and the adjacent flanges 4 and 5, are respectively joined and clamped by means of joint bolts 6.
In order to prevent water seeping out of the earth around the gallery from leaking into the gallery, it is necessary to effect water stopping processing at the respective junctions of the joined flanges. To this end, a band-like joint sealing member 8 is secured by bonding onto one side of the flange surfaces facing gaps 7 between adjacent flange surfaces.
For the illustrated conventional sealing member 8, for example, a well-known water expansible material such as a material obtained by mixing, synthesizing and vulcanizing high hygroscopic resin and synthetic rubber is used. The sealing member 8 is formed into a single layer using the above-mentioned material, The sealing member 8 expands due to infiltration of water W into the joint so as to watertightly seal the gap 7.
In the case where such a sealing material 8 shaped in a single layer is used, however, since the water expansible material has a property of expansion in three dimensions, there occurs considerable expansion A in the lateral direction in addition to the desired expansion in the direction of the thickness of the joint after absorption of the infiltrated water W, in spite of suppression of such expansion in the lateral direction by the fixing action at the junction. Accordingly, there are problems that not only is there apt to be splitting at a portion A of the expansion, but also over time the sealing member 8 may be detached due to a reduction in bonding force due to the effects of expansion stress.
In order to completely perform so-called initial water stopping processing before the sealing member expands due to water absorption by using such a conventional sealing member 8, it is necessary to make the sealing member 8 thicker, in which case not only is the material cost high, but also there occurs frequently a problem of the sealing member 8 more easily becoming dislodged from the junction of the segment 1 in transport or the like.
FIG. 2B depicts another prior art arrangement. In the middle portion in the direction of width of each of the outer surfaces of the flanges 2 and 4 of each of the segments a belt-like fitting groove (for example, a groove 4a in the flange 4) is formed, and a joint member 8 is fixed in each of the fitting grooves. The surface of the joint member 8 projects from the outer surface of each of the flanges 2 and 4.
The flanges 2 and 3 of the respective segments 1A and 1C are fixedly clamped together by three connecting bolts 6, and the flanges 4 and 5 of the respective segments 1A and 1B are fixedly clamped by two connecting bolts 6 such that the joint member 8 is compressed by the a thickness t and the outer surface of the joint member 8 is urged against the outer surface of the flange 5 by elastic force, thereby effecting water stopping processing at the joint junction.
In this arrangement, the joint member 8 must be made thicker so as to sufficiently include the thickness t therein so that the joint member 8 largely projects from the flange 4. Accordingly, not only is a large amount of effort required for screwing on the nuts 6a, but also the projecting edge of the joint member 8 is apt to be caught thereby, causing the joint member 8 to slip out of the fitting groove 4a.
To overcome these difficulties, there have been proposed various arrangements, such as the arrangement shown in FIG. 5A in which as a core of a sealing member 9 a nonexpansible rubber material 10 is filled therein, an arrangement as shown in FIG. 6A in which the shape of a sealing member 11 is maintained by a nonexpansible resin member 12 having an H-shaped cross-section, an arrangement as shown in FIG. 7A in which a nonexpansible rubber member 14 is disposed under a sealing member 13 and joined therewith, etc. There are unsolved problems in the above-mentioned proposals, as follows:
(a) The sealing members 9 and 11 (see FIG. 53 and FIG. 6B, respectively):
Since the bottom surface of the water expansible material portion lower than each of the nonexpansible rubber materials 10 and 12 is bonded to a groove surface, sufficient expanding force cannot be obtained in the direction of thickness of the joint because of interference of the rubber materials 10 and 12.
(b) The sealing member 13 (see FIG. 7B):
It is impossible to completely suppress sideward expansion, although it is possible to prevent the deterioration in bonding force of the bottom surface of the sealing member 13 which occurs over time.